Lampenfabriekeh



April 3. 192s.

LSMQS c. Bol.. A

VACUUM PUMP Filed Nov. l1. 1924 several apertures are provided.

Patented Apr. 3, 1928.

UNITED S'EA'EES rarest CORNELIS BOL, OF EINDHOVEN, NETHERLANDS, ASSIGNOR VTO N. V. PHILIPS GLOEI- LAMPENEABRIEKEN, OE EINDHOVEN, NETHERLANDS.

VACUUM PUMP.

Application filed November 11, 1924., Serial No. 749,199, and in the Netherlands May 5, 1924.

.This invention relates to metal vapour jet pumps and more particularly to pumps in whichmercury vapour is used. llt may, however, also be applied to pumps operating,

Yfor example, with the vapour of metals that pumps have the disadvantage that the vapour` stream through'the annular jet tubes is diiiicult to regulate. As known the vapour speed in the successive v iets in multi-stage mercury vapour jet pumps has to beregitv lated exactly relatively to each otheigin order to ensure a good operation :of the pump. It is not diiicult to choose form and section of vthe central jet tube so that they -meet the requirements; this is, however, a

diiiiculty in the annular iet tubes. as in them even slight diiiierences in the distance between the two walls of the liet tube exercise great influence on the total surfaceof the annular aperturev and consequently on the velocity of the vapour.

In order to obviate the said disadvantage the metal vapour stream through the annular jet tubes is regulated according to the invention by means of a partition in which A This partition is preferably arranged before the outlet end of the annular jet tube corresponding to it. The invention oiiers the advantage in addition to the one already mentioned that. the walls of the annular tubes can be fixed rigidly and in the' correct position relatively to each other in a simple manner.

Very goodV results are obtained with the pump according to the invention, if it is made of met-al.

The successive jet tubes may be branched in the known manner from a common vapour supply tube. In such a construction the partitions provided with apertures are preferably arranged near the points where the vapour supply tube branches to the annular jet tubes which ensures a plain construction.

The apertures may then, for example, be

provided in the wall of the common vapour supply tube. Also according to the invention at the end ot the common vapour supply tube a 4separate inserting member may be arranged consisting of the jet tube for the vapour jet of circular section having fixed to it the partition perforated with apertures corresponding to one or more annular jet tubes. i

The accompanying drawing illustrates,'by 65 way of example, a iet pump operating this mercury vapour. The pump shown in the drawing is entirely made of metal, the invention may, however, also be applied to glass pumps.

The vessel 1 contains a quantity of mer-A cury 15,y which is heated in some suitable manner,'for example, with the aid orn a gas burner. The mercury vapour that is formed, flows through va metal tube 2, which is surrounded by a heat-insulating jacket 3, When the mercury vapour has reached the end of a downwardly bent portion 4 of the tube, it flows partially through a number of apertures 6, and partially through a conical 30 hole 16 in a nozzle 5. The vapour that has passed through the apertures 6, flows then through an annular jet tube,fwhich is formed by a, cylindrical wall 17, supported by legs 20 and the outer wall of the nozzle 5. After 85 n leaving an annular outlet aperture 18 and au outlet aperture 19 of the nozzle 5, the mercury vapour condenses on the wall of a vessel 7 which is constricted at 8 and is cooled by means of a cooling liquid that flows through a cooling vessel 9, having supply and discharge conduits 10 and 11. On one side a high vacuum conduit 12, on the other side a pre-vacuum conduit 13, communicated with the vessel 7. The condensed mercury flows through a tube 14 back again to the vessel 1.

The working of the pump, caused by the two jet-s of mercury vapour, is based on known principles and will herein not be described in detail.

The good results obtained with the pump according to the invention, are owing to the tact that it is easier to provide a number of small apertures ot determined section in a wall, than to regulate exactly an annular aperture ot minute width. It the pump, does not entirely meet the requirements, the small apertures can easily be perfected so that the vapour jet through the annular jet 11e tube obtains the desired velocity or again the apertures may be of regulable size, for example, by arranging two parts adapted to move over eachI other and provided With apertures, this is, in particular, eas-y if the pump is made of metal.

The vapour jet pump according to the inventiou, may be used for different purposes, 'for example, for exhausting electric incandescent lamps, tor which purpose it operates in series with a pre-vacuum pump. The pump according to the invention, may be constructed in such a manner, that it can operate with a comparatively bad prevacuum of for example 20-60 millimetres, Whilst it on the other side is able to' reach a high vacuum of OLO-l micron. The pum can also operate in yseries with another hig vacuum pump for example With a pump of similar construction, in which consequently the pre-vacuum is very good.

What I claim iis:

1. A metal vapour jet pump comprising in combination a central jet and at least one re movable member forming one o1' more annular jet tubes: with said jet, a partition, and apertures in said partition by means of Which the stream of metal vapour through said annular tubes is regulated.

2'. A metal vapour' jet pump comprising in combination a central jet and at least one removable member forming one or more an-- nular jet tubes with said jet, a partition and apertures in said partition, the latter being arranged before the outlet ofY the corresponding annular jet tube and being adapted to regulate the stream of metal vapour through said annular jet tubes.

3. A metal vapour jet pump comprising in combination a central jet and at least one removable member forming with said jets one or more annular jet tubes, said members and said central jet being made of metal, a. partition, and apertures in said partition, the latter bein-gr arranged before the outlet of the corresponding annular jet and being adapted to regulate the stream of metal vapour through said annular jet tubes.

4. A metal vapour jet pump comprising in combination a central jet and at least one metallic removable member forming' with said jet one or more annular jet tubes branching trom a common vapour supply tube, a partition, and apertures in saidpar'- tition, the latter being arranged near the points Where the vapour supply tube branches to said annular jet tube' and adapt ed to regulate the stream of metal vapour through said apertures.

5. A metal vapour Jet pum-p comprrsmg 1n combination a vapour supply tube, a central jet and at least one removable memberv member, the latter being arranged at the end of the vapour supply tube and consist'- ing of the jet tube for the vapour jety of circular section', said member having fixed to it the partition perforated with apertures corresponding to one or more jet tubes.

ln testimon at the city ofy Eindhoven, this 22nd day of October, 1924.-

CO'RNELIS' BOL.

whereof I ax my signature, 

